RedHat perl bug slows TWiki

RedHat (and redhat-derived linux distribs like Fedora and CentOS) have apparently for a long time a bug in their perl packages making perl apps up to 100x slower than normal compared to other distribs like Debian, Ubuntu... See this site for details: Redhat perl. What a tragedy

I checked, the bug is present on the RedHats & CentOS at work (on 26 Aug 2008). However, it does not seem to slow down too much TWiki, but I couldnt compare it with a similar non-redhat hardware. But you should be aware of this bug on RedHat as maybe it could slow down immensely some features / plugins / use cases.

And you should not do any performance testing on redhat-based linuxes while you have this bug.

-- Contributors: ColasNahaboo - 26 Aug 2008

Discussion

I'm working on adding detection to configure atm - its frightening how many systems have been affected (and still are) by a bug reported to RedHat in 2007. Makes TWikiOnDebian and even more significant tool.

-- SvenDowideit - 28 Aug 2008

I am not sure what good a detection algo will be at the moment since no normal admin will know how to fix it. Redhat has not provided any fix. And "compiling your own perl" is not a trivial thing to do.

But if Redhat later provides an update we can warn AND give a one liner instruction to run a "yum update perl". I still also need to see a benchmark between a Redhat with the problem and one using TWiki.

The concept code that shows the problem does show a factor 100 slowdown. Both my Centos and my Fedora machines shows the slow performance with the concept code but I cannot see anything that looks like this when I run TWiki so in reality the bug may hit TWiki by 1%. And then we scare people more with a warning than we help them - unless the fix is possible with a yum update.

-- KennethLavrsen - 28 Aug 2008

One thing that people should be made aware of, is the total lack of care and attention that Redhat has paid to its Paying users. This is apparently not the first time they have broken Perl, and given how long the issue has been known about, and how simple it would be for them to fix, I would suggest not using a RedHat based Linux.

Mind you, I don't intend to do much more than mention the issue in the Configure Perl entry - it won't be orange or red.

-- SvenDowideit - 28 Aug 2008

• showSlowPerl.pl.txt: Show the Perl bless & overload issue using Built in Benchmark module